IO class id,IO class name,Eviction priority,Allocation
0,Unclassified,23,1
1,Superblock,0,1
2,GroupDesc,1,1
3,BlockBitmap,2,1
4,InodeBitmap,3,1
5,Inode,4,1
6,IndirectBlk,5,1
7,Directory,6,1
8,Journal,7,1
9,Extent,8,1
10,Xatrr,9,1
11,<=4KiB,10,1
12,<=16KiB,11,1
13,<=64KiB,12,1
14,<=256KiB,13,1
15,<=1MiB,14,1
16,<=4MiB,15,1
17,<=16MiB,16,1
18,<=64MiB,17,1
19,<=256MiB,18,1
20,<=1GiB,19,1
21,>1GiB,20,1
22,O_DIRECT,21,1
23,Misc,22,1